Speed responsive transmission

Claim 1

In a control mechanism for an automatic speed change mechanism having an input shaft an an output shaft, a fluid coupling comprising a pump wheel driven by a drive engine through said input shaft, a turbine wheel operatively connected to an intermediate shaft, and a gearing means operatively connected to said intermediate shaft and driven thereby, said gearing means comprising friction-engageable means operatively connected to said gearing means for transmitting torque from said fluid coupling to said output shaft, wherein the improvements comprise in combination: a fluid pressure source for supplying hydraulic fluid pressure to actuate said friction engageable means, passage means communicating said fluid pressure source with said friction engageable means, pressure adjusting valve means communicating with said passage means for regulating the fluid pressure therein, a first sensor means drivingly connected to said pump wheel for sensing the rotational speed of said pump wheel and generating a first output signal, the output of said first sensor means being operatively connected to said adjusting valve means, and a second sensor means drivingly connected to said turbine wheel for generating a second output signal in response to the rotational speed of said turbine wheel, the output of said second sensor means being operatively connected to said adjusting valve means, said adjusting valve means acting to increase the hydraulic line pressure in said passage means in response to said first output signal and decreasing said line pressure in said passage means in response to said second output signal.